Status category 1, "No category" - can this happen?

I’ve read in several places (for example here) that status categories are predefined and can’t be changed/added.
Checking the Get all status categories documentation, in the example response there are statuses with names that doesn’t exist and even with id 9 - this seems missleading.

Additionally when checking statuses for my test project it turns out that status ids starts with 2. So just to check I’ve tried https://kboard-staging.atlassian.net/rest/api/3/statuscategory/1 in web browser and received following result:

{"self":"https://kboard-staging.atlassian.net/rest/api/3/statuscategory/1","id":1,"key":"undefined","colorName":"medium-gray","name":"No Category"}

Looks like there is fourth status category. It’s not possible to create status in this category with UI.

But the question is - can there be statuses with status category No Category?
After migration or other operations? Anyone met with such situation?